Mozart in Nairobi's Korogocho slum

Korogocho is one of the largest slums in Nairobi. It means 'crowded shoulder-to-shoulder' in Swahili. [Eva de Vries/Al Jazeera]

Nairobi, Kenya - Korogocho is one of the largest slums in Nairobi, with 150,000 to 200,000 people living on a plot no larger than 1.5 square kilometres. Poverty, crime, drug and alcohol abuse, domestic violence and widespread HIV/Aids make this neighbourhood a tough place to grow up in.

Elisabeth Njoroge wanted to do something for the children living here. As a passionate singer with a strong belief in the transformative power of music, she founded the Ghetto Classics orchestra. Starting out with a crew of 14 singing children in 2008, the project has flourished into a bona fide youth orchestra with more than 80 young musicians.

"Playing music makes you forget the world around you. Troubles can be left behind and there is room again to focus on the positive things in life," Elisabeth says. Music also gives the children the skills to overcome their daily challenges. "If you can master an instrument, you can master life. I honestly believe that," she says.

Every Sunday, children from all corners of Korogocho pile into St John's church, a spacious arena-shaped building with colourfully painted walls bordering a large rubbish dump. As soon as mass is over, they rush to the music room to collect their instruments and start rehearsing.

First, they meet in small groups to practise their parts. The string musicians gather in a room with a panoramic view over the dump. While screeching marabous circle over the rubbish, the violins practise octaves.

At the end of the day, the whole orchestra comes together in the centre of the church to play. The flutes begin softly, then the trombones take their cue. After a short drum solo, all instruments join in to create a beautiful harmony. "Look at their faces," Elisabeth says. "These smiles are the power of music."

Most instruments are donated by music schools or conservatories. They are owned by the orchestra and safely stored in the music room.

Their musical Sunday ends with the most experienced musicians playing a couple of pieces together, directed by conductor Brian Kepher. "He is one of our first members, and now he conducts and studies music. That just goes to show that this programme works," says Elisabeth happily.

Julius,18, is playing the violin in the streets of Korogocho. 'Making music keeps me busy. If I didn't play, I would probably be hanging out on the streets,' he says. [Eva de Vries/Al Jazeera]

'Sometimes I can't stop looking at my saxophone,' says Welma, 11. 'It's just so beautiful and it makes a great powerful sound.' [Eva de Vries/Al Jazeera]

A large rubbish dump lies just on the other side of the wall. Despite the foul smell, Miquel, 14, still loves playing the tuba. 'It's my dream to have my own 10 years from now.' [Eva de Vries/Al Jazeera]

Kennedy, 13, is making music in the playground of a primary school. 'I hope the violin will take me to places I've never been before. I want to become a great musician.' [Eva de Vries/Al Jazeera]

Linet, 17, and Lewinsky, 18, are friends who play the same instrument. 'We really like playing together in the orchestra. When we play, we are like one big family.' [Eva de Vries/Al Jazeera]

Maryanne, 15, who is shy and small for her age, decided to play the cello. 'Playing a big instrument makes me feel so powerful.' [Eva de Vries/Al Jazeera]

'Music gives me joy and helps me achieve my goals,' Nelson, 16, says. And his goals are ambitious. 'I want to travel the world as a musician.' [Eva de Vries/Al Jazeera]

Esther Wendy, 13, may be petite, but her flute produces a big sound. 'When I feel sad, I just think about the flute and the sound it makes. Then I feel happy again.' [Eva de Vries/Al Jazeera]

Edwin, 24, was one of the first members of the orchestra. He now teaches the viola, which is not to be mistaken with the violin. 'A real orchestra really needs a viola,' he says. 'Music always changes my mood. It makes me feel at peace. [Eva de Vries/Al Jazeera]

These boys are practising chords and notes before their lesson starts. They want to be well prepared. [Eva de Vries/Al Jazeera]

The string players are practising scales over and over again. [Eva de Vries/Al Jazeera]

These musicians have already been in the orchestra for a few years. Practising together helps them stay motivated to improve. [Eva de Vries/Al Jazeera]

Elisabeth Njoroge, 'the mother of the orchestra', is watching the children play. She smiles and explains that three flutists are missing, 'They went to boarding school, which is something we really encourage.' [Eva de Vries/Al Jazeera]